Capacity Planning and Workload Forecasting

1
Capacity Planning and Workload Forecasting
2
Definitions (1)

• Capacity the (maximum) amount that a device is
  able to tolerate
• Work
• Throughput
• Storage
• Capacity Plan a strategy to effectively utilize
  the capacity of a device
• Capacity Planning the determination of the
  predicted future time when system saturation will
  occur
• Saturation that point in time when a computer
  system is asked to do more work than it is
  capable of
• Device Saturation that point in time when a
  particular device within a computer system is
  asked to do more work than it is capable of
• Work the transfer of one (1) byte (of data)
  between a processor and a storage device
• Workload the amount of work that is being
  performed by a device or system
• Workload Management the strategy for
  effectively utilizing the performance of work in
  a computer system

3
Definitions (2)

• Background processing that occurs behind the
  scenes and (normally) does not involve direct
  (human) user interaction
• Foreground processing that involves direct
  interaction between (human) users and computers
• Planning Horizon a period of time for which a
  strategy and associated objectives are
  established
• Long range
• Medium range
• Short range
• Initial Load the amount of resources that are
  required at the time an information solution is
  deployed
• Growth Factor the rate of change (?r/?t) in the
  amount of resource used over a planning horizon

4
Definitions (3)

• Performance Constraints business rules that are
  imposed upon the responsiveness of an information
  solution
• Simulation a(n) (parameter- driven,)
  algorithmic approach to modeling the (expected)
  performance of an information solution
• Priority Level the level that an executing
  program is serviced by the computing environment

5
Capacity Planning Schematic
Desired Service Levels
Workload Evolution
System Parameters
Capacity Planning
Cost-effective Alternatives
Saturation Points
Source Menasce, Almeida, Dowdy, Capacity and
Performance Modeling, ISBN 0-13-789546-1
6
Information Technology Components to Consider

• Networks communications paths
• Processor instructions executed
• Memory primary storage
• Files secondary storage
• Work
• Sort
• Storage
• Libraries

• Databases structured permanent storage
• Topology nodes in the network
• Security information protection Software
• Executive
• Applications
• Foreground
• Background

7
Critical Questions

• What is the overall architecture of the current
  environment?
• What is in place?
• What is the this environment capable of?
• What can it do?
• What architecture is needed?
• What will it cost?

8
Importance of Capacity Planning

• User satisfaction
• Image of the enterprise
• Productivity considerations
• Budgetary considerations
• Risk
• Control

9
Capacity Planning and Workload Management -
Relationships
Strategic Plan
Technology Plan
Capacity Plan
Business Vision and Mission
Tactical Plan
Operational Plan
Workload Management
10
Centralized versus Decentralized IS Facilities
Batch
Central Facility
Centralized
Decentralized
Source Menasce, Almeida, Dowdy, Capacity and
Performance Modeling, ISBN 0-13-789546-1
11
Capacity Planning Methodology

1. What is the current installed capacity?
2. What future services should be provided?
3. What are the planned quality goals?
4. What is the most cost effective configuration to
   meet the state goals?

12
Types of Environments

• OLTP Online Transaction Processing
• Transactional activities
• Traditional business transactions
• OLAP Online Analytical Processing
• Algorithmic activities
• Search and/or computation intensive
• Centralized processing
• Single node
• Distributed processing
• Multi-node

13
Capacity Planning Process
IT Environment
A
Alternative A Alternative B Alternative C
Capacity Planning Process
Business Plans
B
C
Product Lines
14
Model-based Capacity Planning
Workload Model
Corporate Plans
Understand Environment
Characterize Workload
Validate and Calibrate
Performance Model
Forecast Workload
Predict Performance
System Alternatives
Validated Model
15
Building the Capacity Plan1. Understand the
Current Environment

• Hardware
• One or more computers
• Share common resources
• Networks
• Interconnect different computers
• Operating System
• Interacts directly with hardware
• Provides services to other software
• Isolates software from hardware anomalies
• Support Software
• Application Programs
• Operational
• Developmental

Operating System
Service Request
Hardware
16
Building the Capacity Plan2. Understanding
capacity (a)

• Theoretical Capacity (of a computing system)
  maximum rate at which such a system can perform
  work
• Throughput (of a computing system) the rate at
  which such a system services requests made of it
• Effective Capacity (of a computing system) the
  largest throughput at which response time remains
  acceptable
• Responsiveness limits the amount of effective
  work processed by a computing system

17
Building the Capacity Plan2. Understanding
capacity (b)
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Building the Capacity Plan3. Computing System
Components
NETWORK
Storage
Memory
I/O
Processor(s)
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Building the Capacity Plan4. Computing System
Metrics

• Cycle time the speed of a processor
• Length ? 10-9 seconds
• Rate ? MHz or GHz
• MIPS millions of instructions/second
  instructions/cycle cycles /sec 10-6
• Benchmarks standard programs used to measure
  component performance
• TPA network performance
• TPB database system performance
• TPC OLTP programs

20
Building the Capacity Plan5. Estimating
Magnetic Disk Performance

• Consists of several elements
• Seek time time required to move the disk arm to
  the destination track
• Rotational delay time required to align the
  target coordinate with the read/write head
• Transfer time the time required to move the
  requested data bits
• Controller time the amount of time (overhead)
  used by the controller
• Average Access Time average seek average
  rotational delay (block size/transfer rate)
  controller time

21
Building the Capacity Plan6. Time Windows (a)

• Consideration of when work occurs
• Peaks
• Valleys

22
Building the Capacity Plan6. Time Windows (b)
What is this graph telling ?
Activity Volume
?
?
?
?
S M T W R F S
S M T W R F S
S M T W R F S
S M T W R F S
Week 1 Week 2 Week 3 Week 4
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Building the Capacity Plan6. Time Windows (c)

• Granularity
• Determining the smallest meaningful unit of time

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Building the Capacity Plan6. Distribution
Considerations

• Every node in the network must be evaluated in a
  like manner

Activity Volume
Time Units
Node
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Building the Capacity Plan7. Service Levels

• Quality of the computing services
• Contractual
• Cost versus benefit
• Competition/business conditions
• Mission criticality
• Previous experience
• Perception
• Generally accepted measures
• MTBF mean time between failures
• MTTR mean time to repair
• Availability (interval length
  downtime)interval length-1

26
Building the Capacity Plan8. Components

• Everything that executes on a computer does work
  and contributes to total workload
• When executing
• Where executing
• So, at any moment in time
• The workload varies
• Capacity plan must project

Operating System
Service Request
Hardware
27
Building the Capacity Plan9. Component and
calculation

• Calculate on an application by application basis
• Consider each of the supporting services used
• Consider nodal implications
• Aggregate and plot
• Adjust to account for unanticipated situations
• At any point, does the estimated aggregate exceed
  the root-mean-square of total capacity (0.707)?
• What risks have been identified

28
The Workload Model

• Representation of actual workload being studied
• Two categories
• Synthetic models
• Combination of actual and specially developed
  components
• Artificial models
• Special purpose programs
• Descriptive parameters

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Synthetic Models

• Experientially based
• Elements/components
• Kernels key programs from existing workload
• Synthetic Programs special purpose programs
  intended to develop critical measurands

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Artificial Model

• Executable
• Suite of computer programs
• Instruction mixes
• Hardware demonstration programs
• Test computational and I/O components
• Kernels
• Code elements from computationally-intensive
  programs
• Measure processor without I/O components
• Synthetic Programs
• Devised code places demand on different
  computing system resources
• Do not resemble real workload
• Different from benchmarks
• Non-executable
• Parametric representation of workload resource
  components

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Artificial Model Parameters

• Typical parameters
• Program interarrival time
• Service demand
• Program size
• Execution mix
• Classes of programs
• Corresponding levels of multiprogramming
• Processor factors
• System load
• Device capability
• File reference location
• Derived parameters
• Frequency distribution of requests
• Request interarrival time distribution
• File referencing behavior
• Size of read and write requests

32
Using the Artificial Model

• Capture key aspects of a computer system
• Relate key aspects
• Mathematical formulae
• Computational algorithms
• Require
• Workload intensity
• Service demand
• Limited representation requires simplifying
  assumptions

33
Workload Characterization Methodology

• Identification of basic components
• Choice of Operating Parameters
• Data collection
• Partitioning the workload
• Resource usage
• Applications
• Geographical orientation
• Functional classes
• Organizational units
• Class type
• Calculating class parameters
• Averaging
• Clustering
• Data analysis
• Scaling techniques
• Clustering algorithms

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Identifying Basic Component of Work

• Job
• Transaction
• Command
• Request
• Result of this step ?
• What does the workload under study consist of?

35
Choice of Characterizing Parameters

• Component representation
• Workload intensity
• Arrival rate
• Number of terminals
• Think time
• Number of simultaneously executing programs
• Service demands
• Specified by k-tuple (Di1, Di2, , Dij)
• K ? number of resources considered
• Dij ? service demand
• i? basic component identifier
• j ? resource identifier

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Data Collection

• Assigns values to parameters of each model
  component
• Generates same number of characterizing tuples as
  number of workload components
• Included tasks
• Identify time windows that define measurement
  sessions
• Monitor and measure system activities during
  defined sessions
• Assign values to all characterizing parameters

37
Partitioning the Workload

• Actual workloads collection of heterogeneous
  component
• Single class representation lack accuracy
• Goal translate heterogeneity into homogeneity
• Divide workload into classes whose populations
  are homogeneous components

38
Partitioning the Workload

• Resource usage classify components based on
  common use of critical resources
• Applications classify components based on class
  of applications
• Subjectization of the enterprise
• Geographical orientation classify components
  based on where they execute
• Functional classes classify components based on
  the computational functions being serviced
• Organizational units classify components based
  on the organizational structure of an enterprise
• Consider organizational culture
• Type classify components based on processing
  mode and associated descriptive parameters
• Interactive (terminal)
• Transaction
• Batch (background)

39
Calculating Class Parameters - Averaging

• Homogeneous components
• Represent a specific value by the average for the
  class
• Consider the tuple (Di1, Di2, , Dik) whose
  arithmetic mean for each parameter is expressed
  as Dj p-1S Dij j 1,2, , k

ki 1
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Calculating Class Parameters - Clustering

• Each clear bullet represents a transaction
  execution
• Resource oriented
• Black bullets represent resultant for a class
  (Ci)
• Statistical description

C1
CPU TIME
C2
C3
I/O TIME
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Calculating Class Parameters Data Analysis

• Set of activities
• Sampling
• Parameter transformation
• Outlier removal
• Distribution options
• Histogram
• Logarithmic

• Sampling
• Specific
• Random
• Parameter transform
• Representation in a standard model
• Outlier removal
• Elimination of extremes

42
Calculating Class Parameters Data Analysis and
Distance
Distance
C1
CPU TIME
C2
C3
I/O TIME
Data Analysis
43
Calculating Class Parameters Scaling

• Used to avoid problems arising from parameters
  with very different values and ranges
• Use a z-distribution for each parameter z
  measured value mean value standard
  deviationwhere the mean and standard deviation
  are standard statistical measures

44
Mean and Standard Deviation Formulae

• Meanx S xi
• Standard Deviations (S(xi x)2)/(n 1))1/2
• Variance ? s2

ni 1
n i 1
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Calculating Class Parameters Clustering
Algorithms

• Minimal spanning tree
• Hierarchical algorithm that starts by considering
  each component of a workload to be a cluster
• Algorithm
• Set initial number of clusters number of
  components
• Determine parameter values of each cluster
• Calculate the inter-cluster distance matrix
• Determine the minimum non-zero element
• Decrement number of clusters
• Repeat steps 2 5 as necessary

• K-means algorithm
• Non-hierarchical clustering technique based on
  finding k points in the workload.
• Algorithm
• Set the number of clusters to k
• Chose k starting points as initial estimates
• Examine each point in the workload allocate it
  to nearest cluster recalculate clusters
  position
• Repeat step 3 as needed until no point changes
  its cluster assignment or a maximum number of
  passes is performed

Identifying natural groups of components based on
resource requirements
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Workload Forecasting

• Computer workloads change as the business
  changes
• New applications
• Changes to existing applications
• Increase in processing volumes by existing
  applications
• Environmental enhancements
• Difficulties
• Obtaining reliable information
• Terminology and communications with
  users/customers
• Needs of the under construction applications
• Latent demand deferred processing requests

47
The Role of Business

• Technical requirements f (business
  requirements)
• Computing capacity f (business base,
  strategic planning)
• Critical applications account for majority of
  computer resource utilization
• What are they?
• Use to identify
• KVI Key Value Indicator
• NBU Natural Business Unit
• FBU Forecasting Business Unit

48
Workload Forecasting Methodology

1. Select applications to be forecasted
2. Identify business units associated with
   applications whose growth will be forecasted
3. Summarize the statistics
4. Collect statistics concerning business units
   being chosen
5. Translate business units into computer demands
6. Forecast future resource demand as a function of
   the business units.

49
Forecasting Techniques

• Moving average
• Exponential smoothing
• Regression methods

50
Moving Average

• Simple forecasting technique
• Allows value for next period to equal average of
  a set of previous observations
• High reliability for (near) steady-state
  situations
• Only one forecast value can be generated at a
  time
• Forecast value calculation ft1 (yt yt-1
  . . . yt-n1 )/n
• Error calculation mean squared error (MSE)
  MSE S (yt ft )/n

n t 1
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Exponential Smoothing

• Similar to moving average
• Greater emphasis on most recent data
• Exponential smoothing formula ft1 ft a
  (yt ft )where ft1 is the forecast for
  period t1 yt is the actual value at time
  t a is the smoothing weight 0 lt a lt 1

52
Regression Methods

• Used to estimate the value of one variable as the
  function of several others
• Simple linear regression y a bxwhere b
  ( S xiyi nxy)/( S xi2 nx2 ) a y bx
  y n-1 S yi x n-1 S xi n
  number of observations

n i 1
n i 1
n i 1
n i 1
53
Performance Prediction Techniques
Low Complexity and Cost High

• Rules of Thumb
• I/O channel utilization lt 35
• CPU utilization lt 80
• Peak utilization lt 90
• Average utilization lt 40

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Workload and Capacity Planning in Conclusion

• Understand the (current) environment
• Specify the service levels
• Perform workload characterization generate a
  workload model
• Develop a performance model
• Validate and calibrate the system model
• Workload model
• Performance model
• Forecast workload growth
• Use system model to analyze performance of
  different system configurations and various
  workload scenarios
• Select the alternative with the best
  cost/performance relationship that satisfies the
  required service levels

55
Capacity Plan Tool Kit
The following slides (55 105) are provided to
the student as anaid in addressing capacity
planning assignments.
56
Building the Capacity Plan

• Start at the application level
• Each application
• One-by-one
• Identify key application components
• Determine growth factors
• Driven by business factors
• Strategic plan
• Tactical plan

57
Components of an Application

• Data
• Functional ? database and file requirements
• Unique contribution to a shared resource
• Program
• Functionality
• Background
• Foreground
• Program size
• Memory occupancy
• Libraries
• Program frequency
• Program type
• Volatility

58
Estimating Data Size (1)

• Critical component of the capacity plan
• Very difficult to estimate early on
• Evolutionary process
• Key questions
• What data does the application require?
• What data is specific to this application?
• What data already exists in the enterprise data
  store?
• What data must be added?
• Does the introduction of this application change
  the amount of data that is already captured in
  the data store?
• How will the data be used?
• How will the data be deployed?

59
Estimating Data Size (2)

• Rule of Experience the data must be understood
  before addressing implementation specifics (such
  as a database or file structure)
• Accuracy is important
• Actual amounts will evolve
• Data sizing is iterative
• Defined process is necessary
• What are the appropriate questions?

60
Estimating Data Size (3)
Problem With reference to the entity-relationship
diagram on the left, prepare an estimate of the
amount of data given the following information1.
All current and former employees are
included. 2. The company has been in existence
for twenty-five years, averaging 400
employees per year. 3. An employee has an
average of six dependents, four
addresses. and five contacts (4 phones
plus an email). 4. There are ten
salary ranges. 5. There are fifty job
codes Describe the process used as well as
the results.
61
Estimating Data Size (4)
ENTITY NAME ENTITY SIZE ENTITY QUANTITY TOTAL SIZE BASIS OF ESTIMATE






62
Estimating Program Requirements (1)

• Essential resources a program will require in
  order to execute
• Memory
• Transactions
• Storage
• Data Operations
• Computer Program a stand-alone set of
  instructions that accept input, process the
  input, and produce results

63
Estimating Program Requirements (2)

• Input considerations
• Type of input
• Stimulus
• Data
• Source of the input
• Interactive
• Message
• File
• Database
• Size of the input how much data
• Number of inputs

64
Estimating Program Requirements (3)

• Output considerations
• Type of output
• Report
• Hardcopy
• Softcopy
• Message
• User-oriented
• Process-oriented
• Destination of the output
• Size of the output
• Number of outputs

65
Estimating Program Requirements (4)

• Program structure
• Algorithms
• Subroutines
• Functions
• I/O operations
• Files
• Database
• Volatility

• Storage
• Working data
• Sort data
• Input/Output data
• Arrays
• Frequency
• How many
• How often

66
Knowing How Much Work is to be Done

• Based on business processes
• Mapped to software transactions
• Key questions
• What are the business processes?
• What software transactions required to execute a
  business process?
• How many
• Business processes?
• Software transactions?
• What physical resources are required?
• When do these processes occur?

67
What is a Business Process?

• Business process
• Set of steps that must be executed to conduct on
  aspect of business
• Set of actions taken upon a business object
• Business rules
• Described in USE CASE
• Conducted by the execution of one or more
  software transactions
• Each software transaction has physical
  requirements
• Depends on the specific nature of the transaction

68
What is a Software Transaction?

• Computer-based program that provides some or all
  of the functionality required to conduct a
  business process
• User interfaces
• Inter-process interfaces
• Input/output operations
• Algorithm processing
• Logic representing business rules
• Network topology
• Level of processing distribution
• Inter-nodal messaging

69
Elements of a Software Transaction

• User interfaces
• HCI or GUI interactions by user
• Number submitted (by user)
• Number transmitted (by software)
• Inter-process interfaces
• Direct invocations (one program to another)
• Number of invocations executed
• Number of times invoked (by another program)
• Input/output interfaces
• File reads and/or writes (media independent)
• Database reads and/or writes
• Indexed or non-indexed
• Reports generated (print or screen)
• Algorithm processing
• Number of machine instructions required to
  execute a business rule
• Network topology
• Number of messages
• Size of messages
• Distribution array

70
Estimating Business Transactions
Volume By Time of Day Volume By Time of Day Volume By Time of Day Volume By Time of Day
0000 To 0600 0600 To 1200 1200 To 1800 1800 To 2400



Software Transactions
Quantity
Nodes in Topology
Transaction Type
Business Process
71
Estimating Software Transactions
FILE-BASED INPUT/OUTPUT OPERATIONS FILE-BASED INPUT/OUTPUT OPERATIONS FILE-BASED INPUT/OUTPUT OPERATIONS FILE-BASED INPUT/OUTPUT OPERATIONS DATABASE INPUT/OUTPUT OPERATIONS DATABASE INPUT/OUTPUT OPERATIONS DATABASE INPUT/OUTPUT OPERATIONS GRAPHICAL USER INTERFACE GRAPHICAL USER INTERFACE REPORTS REPORTS
DISK STORAGE DISK STORAGE TAPE STORAGE TAPE STORAGE DATABASE INPUT/OUTPUT OPERATIONS DATABASE INPUT/OUTPUT OPERATIONS DATABASE INPUT/OUTPUT OPERATIONS GRAPHICAL USER INTERFACE GRAPHICAL USER INTERFACE




SOURCE LANGUAGE INSTRUCTIONS
SOFTWARE TRANSACTION
SCREEN
PRINTER
RECORDS
CHARS
TABLES
INDEXES
CHARS
RECORDS
CHARS
SCREEN NAME
ROWS
FILES
FILES
72
Estimating Message Traffic
SOFTWARE ROUTING SOFTWARE ROUTING NODAL ROUTING NODAL ROUTING
FROM SW TX TO SW TX FROM NODE TO NODE



NUMBER OF MESSAGES
MESSAGE NAME OR IDENTIFIER
MESSAGE SIZE
73
Estimating Frequency

• When will the program execute?
• Timelines
• Frequency distributions
• Nominal
• Maximum
• Minimum

74
Timeline Considerations

• When will the activity occur?

Expected Transaction Volume
Transaction Volume Axis
0000
0600
1200
1800
2400
Daily Transaction Volume Distribution
75
Sizing the Data Store (1)

• Stored data
• Database
• Distribution
• Mirroring
• Files
• Data
• Back up
• Libraries

• Working data
• Sort
• Temporary storage
• Input/output buffering
• Variables
• Media considerations
• Disk
• Tape
• Other

76
Sizing the Data Store (2)

• Functional view
• Technical View
• Structure of the data store
• Requirements of the data store manager

ENTITY NAME ENTITY SIZE ENTITY QUANTITY TOTAL SIZE BASIS OF ESTIMATE






77
Sizing the Data Store (3)

• Files physical storage structure for data
• Governed by the rules of the file management
  system
• Governed by the type of file
• Sequential
• Indexed
• Databases logical storage structure for data
• Databases exist within files
• Governed by the rules of the database management
  system
• Data
• Indexes
• DBMS considerations

78
Files and Databases
Databases exist within files
79
Sizing the Data Store (4)

• Database artifacts are generally sized first
• Tables
• Indexes
• Databases
• Tablespaces
• Files not associated with the database can be
  sized at any time
• Reflect the file structure

80
Sizing the Data Store (5)The Database

• Determine the amount of application data

Column Name Data Type Data Size Rule Actual Size








Then,
Table Name Row Size Rows Growth Rate Table Size

• Complete this table for each row.
• One table is required for each table in the
  database

• Complete this table for each database table

81
Sizing the Data Store (6)The Database

• Calculate the physical space requirements for
  data on a table-by-table basis
• Number of rows in the table
• Median length of a row
• Block size defined to the DBMS
• Overflow percentage
• Using the process
• Determine the number of rows that can be stored
  in one block
• Determine the number of blocks that are required
• Determine the total space requirement
• Include an estimation safety factor

82
Sizing the Data Store (7)The Database

• Number of rows that can be stored in one block
  (nr) nr ((blocksize (header footer))
  overhead)/median row size
• Number of blocks required (nb) nb total number
  of rows/nr
• Amount of disk space required (dsp) dsp nb
  blocksize
• Estimating factor is an increasing multiplier
  based on the estimators presumption of accuracy

83
Sizing the Data Store (8)The Database

• Index sizes must now be calculated for each index
  declared via a CREATE INDEX statement
• Primary key size nr (bytespk bytespa)
• Number of estimated rows in a table
• Number of bytes in the primary key
• Number of bytes in the pointer address
• (Each) search index nr (bytessk bytespa)
• Estimated number of rows
• Number of bytes in the index key
• Number of bytes in the pointer address

84
Sizing the Data Store (9)The Database
Assignment You are to size this database
usingthe preceding materials. Assumethat
EMPLOYEE will have a searchindex on JOB_CODE and
DATE_OF_HIREand that CONTACT will have a search
keyof AREA_CODE. ADDRESS will have a search
key of ZIP_CODE. Explain what considerations
must be made to accommodate foreign keys
85
Sizing the Data Store (10)Non-Database Files

• Ordinary files f ((m 8) n) e
• Median size of a data record in bytes
• Number of records estimated
• 8 bytes per record (file overhead)
• Estimating accuracy factor
• Index files f (((m 8) n) i p) e
• Median size of a data record in bytes
• Number of records estimated
• Estimating accuracy factor
• Size of the index
• Number of bytes in the index
• Size of the address pointer

Approximate refer to the appropriate
Operating System documentation
86
Sizing the Data Store (11)Non-Database Files
Assignment In unloading this database for
archivingpurposes, a sequential file will be
created.The created file will contain a
completeset of data about employees,
includingall address and contact information.
Thefile will also contain a complete set ofdata
about dependents, including alladdress and
contact information as wellas some form of
connectivity to theemployee. You are to 1.
Describe each record that will be
created.2. Size the sequential file.3.
Explain the process that was followed.
87
Sizing the Application (1)Considerations

• Functions performed
• Background
• Foreground
• Data stores accessed
• Files
• Databases
• Input/Output operations performed
• Read/Write
• Logical/Physical
• Algorithms
• Complexity
• Frequency
• Concurrency

88
Sizing the Application (2)

• Generally separate by background versus
  foreground
• Key measures
• Transactions
• Input/Output operations
• Complexity (of algorithms)

89
Sizing the Application (3)Definitions

• Transaction
• Set of instructions needed to execute one
  instance of a business process
• Work performed by a computer to (successfully)
  execute these (set of) instructions
• Input
• Physical the transfer of one physical unit of
  data (usually referred to as a block) to memory
  from storage
• Logical the transfer of one logical unit of
  data (such as a record in a file or a row in a
  database table) to memory from storage
• Output
• physical the transfer of one physical unit of
  data from memory to a storage medium
• Magnetic
• Optical
• Electronic
• Paper

90
Sizing the Application (4)
Transaction Physical Input/Output Operations Physical Input/Output Operations Input/Output Buffer Space Input/Output Buffer Space Source Language Instructions (SLI) I/O Time (_at_ 30ms/IO SLI Time (_at_ 10ms/SLI Sort Buffer Space Total Space Total Time
Transaction Read Write Read Write Source Language Instructions (SLI) I/O Time (_at_ 30ms/IO SLI Time (_at_ 10ms/SLI Sort Buffer Space Total Space Total Time




91
Sizing the Application (5)

• Data is a principal driver
• Good design is essential
• Use optimizers to minimize executing instructions
• Apply complexity factors
• Size by instance

92
Considerations for Topology

• How many nodes?
• What functions at each node?
• What data at each node?
• How many functions at each node?
• How much network traffic between nodes?
• How many messages sent?
• How many messages received?

93
Implications of Topology
NODE 5
NODE 4
NODE 3
NODE 2
NODE 1
94
Implications of Topology

• Nodal volumes not necessarily identical
• Critical considerations
• How many transactions?
• In which time frame?
• How many messages?
• How many users?
• Requires two views
• Nodal view
• System view

95
Implications of Topology

• Assignment
• For the topology illustrated in the diagram to
  the left, develop a process and the associated
  set of tools that you would use to establish the
  resource requirements for a new application that
  is currently in development.
• Demonstrate the viability of your approachgiven
  the following constraints
• Number of users Baltimore (100), Ft Wayne
  (50), Pittsburgh (75), Kansas City (40),
  Missoula (30), and Denver (200)
• Each user initiates an average of 1 transaction
  every two minutes
• Each site works a standard 8-hour day from 8 AM
  to 5 PM (local time) Monday - Friday
• The database is replicated and consolidated
  each workday evening (in Denver)
• Each local database is backed up each weekday
  evening
• Users will send one message/per hour to each of
  the other nodes and two messages per hour
  within their own node
• A transaction accesses the database and four
  80-byte fixed length files. There are no sorts.
  
• Make any assumptions needed to complete the task.
  

96
The Meaning of Work

• What is work?
• Accomplishing a defined task
• How is work defined?
• The transfer of one byte of data between a
  processor and secondary storage
• What is meant by the term work in a computer?
• Input operations performed
• Instructions executed
• Output operations performed
• How is work measured?
• Memory occupancy
• Instructions executed per unit of time
• What about processor speed?
• Describes how fast work can be accomplished

97
Work Over Time

• When is the work done?
• Peaks and valleys
• When
• Where
• Significance of 7 x 24 x 365
• Does the hour matter?
• Does the day matter?
• Does the month matter?
• Does the season matter?

98
Profiling the Requirements of Time

• Time increments are application and installation
  dependent
• Relevant time intervals
• Hour
• Day
• Week
• Month
• Year
• As Required always possible

There is a real possibility of ann-dimensional
problem with regard to time
99
What Must Be Considered (1)

• Resource requirements of individual applications
• Over time
• Over the topology
• Shared resource requirements
• What are shared resources?
• What are the requirements for their usegt
• Over time
• Over the topology

100
What Must Be Considered (2)
INDIVIDUAL INDIVIDUAL SHARED SHARED
TIME TOPOLOGY TIME TOPOLOGY
PROCESSOR
MEMORY
STORAGE
COMMUNICATION
FACTOR
RESOURCE
101
Capacity Planning

• The science of determining how much resource will
  be required over a planning horizon
• Considerations
• Critical resources
• Machine capabilities
• Workload characteristics
• Normal workload
• Peaks and valleys
• Change over time
• Growth
• Reduction
• System factors

102
Capacity Planning Considerations (1)

• Normal load the expected amount of resource to
  be used under usual circumstances
• Peak load the maximum amount of resource to be
  used under exceptional circumstances

103
Capacity Planning Considerations (2)
100
Contingency to accommodate spikes,priorities,
and/or contention
Contingency Value
Available for Normal Use
0
104
Capacity Planning Considerations (3)

• What do you need now?
• What do you have?
• What will you need at each increment in the
  planning horizon?
• What is the plan?
• What are the risks
• Unanticipated demand
• Unexpected surplus
• Change in the business
• The importance of being earnest
• Right-sizing the environment

105
Developing a Capacity PlanExercise

• As the systems engineering team for a mid-sized,
  high growth manufacturing company with an
  international presence, identify the source
  materials you will require in order to develop
  the enterprises capacity plan over a nominal
  business strategic planning horizon.
• Describe the process that you will employ to
  develop the plan.
• Describe the process that you will employ to keep
  the plan current by updating it on an annual
  basis.
• Describe how your role differs from the role of
  the application owner.